The disclosure relates to a pressure valve, in particular to a directly controlled pressure-limiting valve.
The applicant's data sheet RD 25010-B/10.06 discloses such a pressure valve. Said valve has, as a valve housing, a sleeve which can be screwed into a control block and in which a valve spring is arranged. Said valve spring is supported on a valve plate and applies a spring force to a valve body of the pressure valve in the direction of the valve seat thereof. A connection between a pressure port and a tank port can be controlled by means of the valve body. In this context, a pressure force, counteracting the spring force, of a pressure medium of the pressure port can be applied to the valve body. If the pressure force acting on the valve body exceeds the spring force, the valve body lifts off from its valve seat and opens a pressure medium connection to the spring space of the valve spring, which spring space is connected to the tank port.
The spring plate can be adjusted in the axial direction in order to change the spring force of the valve spring by means of an adjustment mechanism which is arranged in a closure element of the sleeve, wherein the closure element is screwed into the sleeve. The adjustment mechanism has a shaft with a threaded section which can be screwed into an inner thread of the sleeve and with a securing section for the spring plate. The securing section has a radially set back end section about which the spring plate engages. The spring plate has for this purpose a continuous drilled hole via which it is plugged onto the securing section. The spring plate is supported on an annular end face of the securing section by means of its end face which points away from the valve spring, which annular end face is formed by the set back end section. The spring plate is then secured to the shaft in the axial direction by means of a circlip. The end face of the spring plate also serves as a bearing shoulder via which the spring plate can be supported on the closure element. The shaft can be screwed relative to the sleeve from the outside with a tool. If the pressure valve is used as a safety valve, the shaft and the valve housing can be configured in such a way that they can be provided with a lead seal.
A disadvantage with this solution is that during the adjustment or screwing of the shaft of the adjustment mechanism in order to change the spring force of the valve spring, such a high torque can be transmitted to the closure element or the sleeve that the latter is undesirably released from its screwed and secured position. This is the case, in particular, when the spring plate bears with its end face against the closure element, as a result of which a torque can then be transmitted to the closure element via the shaft and via the spring plate which is secured thereto. This effect is amplified if there is a pressure in the spring space. If the closure element and/or the sleeve are/is unintentionally released, this can lead in an extremely disadvantageous fashion to, for example, pressure medium escaping from the pressure valve. If the closure element is screwed out completely, this said spring element could be accelerated strongly in the direction away from the valve housing owing to the relaxing valve spring and/or the pressure force, and in the worst case could cause injuries to persons.
In view of the above, the disclosure is based on the object of providing a pressure valve which has a high level of safety.